Which type of consideration demands action or payment to be valid?

The concept of consideration in contract law refers to something of value that is exchanged between parties to a contract. Real consideration specifically refers to an actual exchange of value, which can be in the form of a tangible action or a payment. This is fundamental to the formation of a valid contract, as both parties must provide something of value for the agreement to be enforceable.

In the case of real consideration, the involvement of either action or payment signifies that the parties have a mutual interest that facilitates the exchange. This is crucial because a contract without consideration typically lacks the necessary legal enforceability.

While other forms of consideration exist, they do not emphasize the notion of an actual action or payment in the way that real consideration does. The options related to negative, illegal, and public considerations do not pertain to valid mutual exchanges necessary for a contract’s formation. Thus, real consideration stands out as the correct choice since it directly involves active participation or payment necessary for the validity of the contractual agreement.